Apparatus for pulling open the ends of tube sections of plastics material



United States Patent Inventor Fritz Achelpohl Lengerich of Westphalia, Germany App]. No. 723,991 Filed April 25, 1968 Patented Dec. 8, 1970 Assignee Windmoller & Holscher Lengerich of Westphalia, Germany Priority MayZ, 1967 Germany No. W43900 APPARATUS FOR PULLING OPEN THE ENDS 0F TUBE SECTIONS OF PLASTICS MATERIAL 8 Claims, 3 Drawing Figs.

US. Cl .4 93/28 [51] lnt.C| B3lb l/76 [50] Field of Search 93/22, 28, 8; 53/386 [56] References Cited UNITED STATES PATENTS 3,398,503 8/1968 Bertoglio 53/386 3,446,121 5/1969 Achelpohl 93/28 Primary Examiner-H. A. Kilby, Jr. Attorney-Fleit, Gipple & Jacobson ABSTRACT: Two vacuum beams revolve in opposite directions and are provided with vacuum openings. The vacuum conduits leading to the vacuum beams are provided with a valve, which is disposed close to the vacuum beams and is automatically opened when the vacuum beams are closed and is held open during the pulling-open operation.

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HTTDRIUEyS APPARATUS FOR PULLHNG OPEN THE ENDS F TUBE SECTIONS OF PLASTICS MATERIAL This invention relates to an improvement in an apparatus for pulling open the ends of tube sections of plastics material sheeting. Such apparatus has been disclosed in the U.S. Pat. Ser. No. 638,278, filed May 15, i967.

The apparatus covered by said prior disclosure comprises two vacuum beams, which revolve in opposite directions and are provided with vacuum openings. It is an object of the invention covered by said prior disclosure to enable a fast and reliable pulling-open also of tube sections which consist of plastics material sheeting in two snugly contacting plies, to accomplish this object, said prior disclosure teaches to form the lower vacuum beam with undulations extending right angles to the open edge of the tube section, and to provide the vacuum openings of the lower vacuum beam in the valleys of the undulations, and the vacuum openings in the upper vacuum beam in registry with the crests of the undulations of the lower vacuum beam. This design ensures that one ply of the tube section, preferably the lower ply, is drawn into the valleys of the undulations of the lower vacuum beam when the vacuum beams are still completely closed so that this corrugating deformation of the lower tube ply results in the formation of passages between the two plies and air can readily enter through said passages when the vacuum beams are moved apart as the rotationof the links which carry the vacuum beams is continued.

Hence, the drawing of the lower ply into the valleys of the undulations of the undulated lower.vacuum took, whereby one tube is corrugated to form passages between the two plies,

is to be effected when the vacuum beams are completely closed and has the purpose to 'permitair to enter these passages when thevacuum beams are moved apart as the rota tional movement is continues continued. Because the vacuum beams are actually closed only within a small arc of the rotational movement, only a very short period of time is available for the desired drawing of one pl-y into the valleys of the undulations, particularly at the high speeds which are desired. For this reason it is essential to apply the full vacuum immediately when the vacuum beams have been closed. On the other hand, a vacuum cannot be created in the vacuum openings until they have been closed by being covered by the sheeting. When the vacuum openings are open, only air is drawn, which action does not require an appreciable negative pressure. As soon as the vacuum openings are covered by the tube plies, a vacuum can be applied in that air is drawn from the vacuum conduits,

which were previously approximately under atmospheric pressure. For instance, to produce a vacuum of 80-90 percent, it is necessary to suck off 80490 percent of the air contained in the vacuum conduits. On the other'hand, the conduits leading to the vacuum pump cannot be made as short as desired a, because the vacuum pump cannot be, accommodated in the opening station itself.

It is an object of the present invention to enable in an apparatus according to said prior disclosure, but also independently thereof, in pulling-open apparatus having two vacuum beams which are provided with vacuum openings and revolve in opposite directions, a very fast application of a vacuum so that the full vacuum becomes effective immediately and the short time during which the vacuum beams are closed is utilized as fully as possible particularly in apparatus according to said prior disclosure.

To accomplish that object, it is suggested to provide the vacuum conduits leading to the vacuum beams with valves, which are disposed close to the vacuum beams and are automatically opened when the vacuum beams are closed and are held open during the pulling-open operation. This arrangement ensures that the fullvacuum is constantly available from the vacuum pump as far as the valve and is applied by a very short conduit to the vacuum openings of the vacuum beams when the valve is open so that the application of the full vacuum to the vacuum openings is not appreciably delayed. The above-mentioned objects are thus accomplished.

Each of the vacuum conduits connected to the two vacuum beams may desirably have a stationary connection fitting, which cooperates with a connection. fitting provided on that part of the vacuum conduit which is connected to the vacuum beam, which latter fitting is arranged to move in response to the movement of the vacuum beam,-a valve member being arranged to close the opening of the fixed connection fitting except during the closing period, and the opening of the movable connection fitting being connected to the opening of the fixed connection fitting during the suction period. It will also be desirable in the practice of the invention if each of the fixed connection fittings is connected by a flexible conduit to the vacuum source and adjustable in the direction of the movement of the movable connection fitting sothat the open time can be adjusted separately for each vacuum beam.

Each of the movable connection fittings may be provided in a disk which'rotates with the associated vacuum beam, and each movable connection fitting may have milled aperture which communicates with the vacuum openings of the vacuum beam and has a length selected in accordance with the desired duration of the suction period, whereas a valve face of the disk is in sealing contact with the mouth of the stationary connection fitting except during the suction period. The valve according to this desirable design may be further improved in that the stationary connection fitting is provided in a valve disk which is axially movable and spring-urged towards the disk which rotates on the axis of the valve disk said rotating disk sliding on an annular contact zone of the valve disk and the openings of the connection fittings being disposed in said annular contact zone.

The movable connection fittings are suitably operatively connected to the vacuum beams by resilient connecting members so that the rotational movement of the rotating disks is derived from the vacuum 'beams, The resilient connecting members are provided because each vacuum beam is positively driven by two cranks and the movable connection fittings are driven by the rotating disks so that even very small inaccuracies of these drive means could result in an impermissible constraint at the bearings if the resilient connecting members were not provided.

It will also be desirable if the vacuum beams are mounted in their drive means with a freedom of a spring-opposed movement at right angles tothe plane of the workpiece and flexible connections are provided between the movable connection fittings and the vacuum conduits connected to the vacuum beams so that that part of each vacuum conduit which extends between the movable connection fitting and the vacuum beam can adjust itself to the spring-opposed movements of the vacuum beams. The freedom of movement of the vacuum beams or at least of the upper vacuum beam at right angles to the plane of workpiece travel is desirable because it enables an adaptation to the thickness of each tube section to be opened. If the vacuum beams are resiliently connected to their drive cranks, as has just been described, it will also be desirable if the resilient connecting members between the movable connection fittings and the vacuum beams. are connected to intermediate brackets rather than to the vacuum beams themselves and said intermediate brackets are nonresiliently but rotatably mounted on the cranks and carry the holders for the resiliently mounted vacuum beams. This arrangement makes allowance for the fact that the resilient connecting members for mounting and driving the rotating disks cannot follow the relative movements of the vacuum beams because said connecting members are driven by the rotating disks The invention will be explained more fully hereinafter with reference to the drawings, which show an embodiment by way i of example. Specifically,

FIG. 1 is a vertical sectional view taken on line 11-" in FIG. 2 and showing the pulling-open apparatus according to the invention,

FIG. 2 is a sectional view taken on line lI-ll in FIG. 1, and

FIG. 3 is an enlarged view taken in the direction of the arrow III in FIG. 2 and showing a detail.

The drawings show one of two pulling-open units, which are symmetrically disposed on both sides of the machine. A tube section 76-to be pulled open at its ends is shown in dash-anddot lines to lie between both units. Vacuum beams 77 and 78 are shown in their closed position. FIG. 1 shows also in dashdot lines the vacuum beams in an open position at 77', 78. The vacuum beams are rotatably connected to cranks 7982 by crankpins 83-86. The cranks are clamped to shafts 87- 90, which are rotatably mounted in a vertical frame plate 91. At the end opposite to the crank, each of the shafts is provided with one of gears 92-95. The gears 92-95 are positively coupled by two additional meshing gears 96 and 97, which are mounted in the frame plate and are driven from the machine by means not shown to perform one revolution per machine cycle so that the vacuum beams perform one revolution per workpiece. The frame plate 91 has a base 98, which is adjustable on a sliding guide 99 by means of a handwheel 102 carried by a screw 101 mounted in the side frame 100 of the machine to enable an adjustment to different bag end widths.

The main vacuum conduit 104 extends through an aperture 103 in the frame and moves in unison with the adjusting move ments of the pulling-open unitbecause the conduit 104 is connected by a flexible tubing 105 'to the vacuum pump.'The con duit 104 is laterally spaced from the vertical center plane (see FIG. 1) because a central arrangement is prevented by the idler gears-96 and 97. The conduit 104 is connected at its inner end to two branch conduits 106 and 107 leading to upper and lower square fittings 108 and 109, respectively. Each of these square fittings has a cylindrical extension 110, which extends through an associated, circumferentially curved slot 111 in the mounting plate 91 to an associated valve disk 112. The extension 110 is secured in the valve disk 112 by an additional cylindrical extension 113, the end of which is flush with the valve disk 112. Each square fitting 108 and 109 has a blind bore 114; which is connected by a transverse bore 115 to an associated, flexible connecting tubing 106 or 107.

Each valve disk 112 is mounted on an associated flanged bearing 116 for movement in the circumferential direction and is held against rotation by an associated pin 117, which is secured in the frame plate 91 in an associated, circumferentially curved slot 118 for adjustment in the circumferential direction. A collar 119 on each pin 117 extends into an associated bore of the associated valve disk 112 to hold the same against a circumferential movement in the adjusted position. Because the vacuum tubings 105, 106, and 107 are flexible, the valve disc 112 and the square fittings 108 and 109 can be rotated along the slots'lll and 118. This adjustment of each valve disk 112 and ofv the vacuum bore 114 opening in the inside plane of such disk will determine the angular positions of the vacuum beams at the beginning and end of the application of a vacuum thereto so that these positions can be exactly adjusted for each of the upper and lower vacuum beams.

Each of the valve disks 112 is axially slidable on its flange bearing 116 and pin collar 119 and is urged toward an associated rotary disk 123 by six compression springs 120, which are accommodated in bores 122 of the mounting plate 91. These bores 122 are closed on the outside by covers 121. Each rotary disk 123 is rotatably mounted on an associated shaft 124, which is rotatably mounted in an associated one of the flange bearings 116. The rotary disks present an annular end face 125 contacting the valve disks 116. This contacting end face lies within the range of the vacuum bores 114 so that the latter are normally closed by the end faces 125 and the full vacuum is continuously maintained as far as to said end faces.

Each end face 125 is formed in a part of its circumferential extent with a circumferentially curved, milled aperture 126 (see also FIG. 1). On its side which is nearer to the vacuum beams and in the drawing is remote from the bores 114, each of said apertures is connected to an associated tube 127, which is held in an associated block 128 of resilient material. Each block 128 is firmly connected to an associated one of the vacuum beams 77 and 78. Each tube 127 is rotatably mounted in a bushing 130 inserted in an aperture 129 of the associated rotary disk 123. Each of the bearing s is sealed by an associated sealing ring 131. t

The resilient mounting of the tubes 127 in the blocks 128 relative to the vacuum beams makes allowance for the fact that each vacuum beam is positively driven by two cranks and the tubes 127 are positively driven by'therotary disks 123 so that a perfect registry of the tubes 127 with the blocks 128 connected to the vacuum beams cannot be expected. Unless the blocks 128 were resilient in accordance with the invention, even very slight inaccuracies would result in a nonpermissible constraint at the bearings.

Each vacuum beam is connected by an associated U-pipe 132 and a flexible sleeve 133 to that end of the associated pipe 127 which protrudes from the block 128. The need for this flexible joint will be explained hereinafter.

The drawings show the position at the beginning of the suction period. When the leading end of each aperture 126. is in registry with the associated bore 114 during the rotation of the rotary disks 123, the bores 114 communicate through tubes 127 and 132 with the vacuum openings of the respective vacuum beams 77 and 78. Because the distance from the milled apertures to the vacuum openings is short, the full vacuum maintained in the bore 114 is very soon applied also the vacuum openings. As the rotation of the rotary disk 123 is continued, the tubes 127 move progressively. away from the bores 114 but are still connected to them by the milled apertures 126 as long as the latter extend still to the bores 114. When the trailing end of the milled apertures 126 has left the bores 114, the application of the vacuum to the vacuum openings is terminated. The beginning of the application of the vacuum can be separately adjusted for the upper and lower vacuum beams as required by an adjustment of the valved disks 112 and of the bores 114 in the circumferential direction as has been described hereinbefore.

The flexible connection established by the sleeves 133 between the tubes 127 and the U-tubes 132, which are rigidly connected to the vacuum beams, is required at least for the upper vacuum beam 78 because the same is mounted on its driving cranks 81 and 82 for movement'at right angles to its lower active surface so as to be adjustable to different thicknesses of the workpieces entering between the vacuum beams and to be able to yield in the case of an upsetting of the workpiece. For this reason, bearing blocks 134 and 135 (FIGS. 1 and 3) are mounted on the crankpins 85 and 86 of the upper cranks 81 and 82 and the vacuum beam 78 is suspended from said bearing blocks with the aid of pins 136, which are movable upwardly in the bearing blocks against the pressure of a spring 137. Lock nuts 138 enable an adjustment of the initial height of the vacuum beam and of the working gap between the tube vacuum beams; this working gap should correspond to the thickness of the workpiece.

Because the blocks 128 which carry and drive the tubes 127 and rotary disks 123 and their vacuum beams cannot follow the movement of the upper vacuum beam 78 relative to its mounting, the block 128 associated with the upper vacuum beam is not screw-connected to the vacuum beam, as is the block 128 associated with the lower vacuum beam 77, but is screw-connected to a flat steel bar 139, which is secured by screws 140 to beating blocks 134, 135. FIG. 3 shows that the blocks 128 consist of two parts each and are held together by the fixing screws 141 in order to facilitate the assembling.

To ensure that the application of the vacuum to the vacuum beams will be terminated instantaneously, the valve disks 112 have bores, not shown, which lead into the open and connect the milled apertures 126 to the atmosphere when the open phase has been terminated.

Iclaim:

1. Apparatus for pulling-open the ends of tube sections of plastics material sheeting, comprising two vacuum beams which revolve in opposite directions and are provided with vacuum openings, characterized in that the vacuum conduits leading to the vacuumbeams are provided with valves, which are disposed close to the vacuum beams and are automatically opened when the vacuum beams are closed and are held open during the pulling-open operation.

2. Apparatus according to claim 1, characterized in that each of the vacuum conduits connected to the two vacuum beams has a stationary connection fitting, which cooperates with a connection fitting provided on that part of the vacuum conduit which is connected to the vacuum beam, which latter fitting is arranged to move in response to the movement of the vacuum beam, a valve member being arranged to close the opening of the fixed connection fitting except during the closing period, and the opening of the movable connection fitting being connected to the opening of the fixed connection fitting during the suction period.

3. Apparatus according to claim 2, characterized in that the fixed connection fitting is connected by a flexible conduit to the vacuum source and adjustable in the direction of the movement of the movable connection fitting.

4. Apparatus according to claim 2 characterized in that the movable connection fitting is provided in a disk which rotates with the vacuum beam, and the movable connection fitting has a milled aperture which communicates with the vacuum openings of the vacuum beam andhas a length selected in accordance with the desired duration of the suction period,

whereas a valve face of the disk is in sealing contact with the mouth of the stationary connection fitting except during the suction period.

5. Apparatus according to claim 4, characterized in that the stationary connection fitting isprovided in a valve disk which is axially movable and spring-urged towards the disk which rotates on the axis of the valve disk said rotating disk sliding on an annular contact zone of the valve disk and the openings of the connection fittings being disposedin said annular contact zone.

6. Apparatus according to any of claim 2 characterized in that the movable connection fittings are operatively connected to the vacuum beams by resilient connecting members.

7. Apparatus according to any of claim 2 characterized in that the vacuum beams are mountedlin their drive means with a freedom of a spring-opposed movement at right angles to the plane of the workpiece and flexible connections are provided between the movable connection fittings and the vacuum conduits connected to the vacuum beams.

8. Apparatus according to claim 7., characterized in that the resilient connecting members between the movable connection fittings and the vacuum beams are connected to intermediate brackets which are nonresiliently but rotatably connected to the cranks for the vacuum beams and carry the holders for the resiliently mounted vacuum beams. 

